The present invention is directed generally to epoxy fluoropolymer compositions for use as protective surface coatings on various substrates such as metal, wood, plastic, paper and the like. This invention relates to novel 100 percent solids epoxy fluoropolymer coating compositions. In another aspect, the invention relates to novel coating compositions and the process for producing the coating compositions which have excellent corrosion resistance and good adhesion as well as good release properties and hydrophobicity.
There is demand in the industry for protective coatings that will withstand the effects of a variety of severe environmental conditions. Many varieties of coating compositions are currently available that are based on various polymeric materials. Fluorocarbon polymers are generally thermoplastic with, however, a high melting point; thus there are significant economic and technical barriers that must be overcome when using them. However, polytetrafluoroethylene is not thermoplastic and therefore must be fabricated. Generally, in the fabrication process the resin is compacted to preform and then is sintered at temperatures above 700 degrees F. As such, using polytetrafluoroethylene is energy intensive and only simple shapes can be realized. Fluoropolymer coating compositions exhibit nonstick properties and adhesion to metal at temperatures around 700 degrees F. In accordance with this invention, it has been discovered that fluorocarbon polymers can be processed at ambient or relatively low temperatures.
Most coating systems used today are solvent based or water based. Solvent based coating are disadvantageous in that large amounts of volatile organic solvents are present. These solvents may be costly and hazardous. The solvents must be removed from the final coatings which required considerable thermal energy. Further, if hazardous, the solvents must be recovered or incinerated as they may not be exhausted into the environment. Water based coatings are disadvantageous in that they are not continuous and have been found to contain more pinholes and voids than the solvent based coatings.
As a result, the search for an essentially solvent-free coating process has led to the use of solventless systems. The advantages of a solventless coating system includes the minimization of surface defects due to the absence of solvents and excellent heat and chemical resistance.
It is an object of this invention to provide an epoxy fluoropolymer coating composition in a 100 percent solids, solvent free system to avoid use of cyclable solvents. It is another object of this invention to produce a corrosion resistant coating that is cured at ambient or relatively low temperatures. It is another object of this invention to form a coating composition with the excellent adhesion, good wetting, good cohesion, good hydrophobicity, excellent chemical resistance and good release properties. It is another object of this invention to produce a coating that is resistant to a variety of aggressive environmental conditions.
These and other objects, together with the advantages over known methods shall become apparent from the specifications which follows and are accomplished by the invention as hereinafter described and claimed.